Recompletion of wells



FIG. B.

Y. DR E H ...m 9 m ms. m C U T 1B my M f .f\ VWRM, A 1 .avf/n. .v. .....wH../..v./L.. m56 www DMW@ ..wYs/...r/TW/.z.$15. /....Y.. w .....y/z W R OMI. LOE FJM l :c Q Y D R H3 EF F. A. SMITH ETAL Filed March 2. 1964 RECOMPLETION oF WELLS FIG. 2.

Sept. 27, 1966 PAcKER GRANULAELH- FIG. lA.

Vinto the well bore.

Y 3,275,077 RECOIVIPLETION OF WELLS VFloyd A. Smith, Tulsa, Okla., and Joseph W. Graybea-l,

This invention relates to recompletion of wells, and Amore particularly toa technique for plugging only selected perforations in a cased perforated Well bore.

During recompletion of wells it is the usual practice to-kill the well before `recompletion operations are begun in order to stop the flow of connate earth uids After lthe recompletion operations have been finished, often it is desirable to plug certain of the perforations in the well bore, such as when ,it has been found that water is entering the well through one or more of the -lowermost perfor-ations. It has been the usual practice to squeeze a cement slurry into all of the perforations and, after the cement llas hardened, to reperforate the Well bore. Such an operation is undesirable for at least two reasons. The technique of cementing and perforating is expensive inasmuch as ia consid- -erable amount of pipe handling and wire line operations Vare necessary. Furthermore, perforation inevitably ,causes a certain amount of damage to the casing and cement sheath therearound. In addition, the cements currently in use may prematurely set in the casingand/or tubing string and lead to expensive lis'hing operations, and may even cause loss of the well.

In accordance with the teachings of the present invention, particulated sulfur is packed into #all of the perforations, -and the sulfur in selected perforations is heated until :the particulated sulfur therein is fused together. Thereafter, the well is produced toremove the unfused sulfur particles from the perforations other than the selected perforations. i

Objects and features of the invention which are not apparent from the above discussion will become evident upon consideration of the following detailed description of the invention taken in connection with the accompanying drawing,` wherein:

FIGS. 1, 2, and 3 tare schematic presentations of an oil well installation, partially in cross section, illustrating several ofthe steps performed in accordance with the invention; and

FIGS. 1A and 2A are enlarged viewsV of portions of FIGS. 1 and 2, respectively, for the purpose of better illustrating the manner in which sulfur is packed into perfor-ations and fused therein.

available, such as Invermul, sold by the Baroid Division of the National Lead Company; Protectomul, lsold by the Magnet Cove Barium Corporation; and Black Magic, sold `by Oil Blase, Inc.` However, `the preferred vehicle is oil-in-water emulsion comprising about 83% to about 98% by volume of water, from Aabout 1.5% to about 10% by volume of oil, a water-soluble salt of` lignin sulfonic acid in the range from about0.75% to about 1% by weight to which is @added from about l to 100, and preferably from about 5 t 50 pounds of particulated United States Patent() V-perforations 19.

31,275,077 Patented Sept. 27, 1966 ceN sulfur per barrel of water and oil, said sulfur having particle sizes in the range of 4 to 325 mesh. The oil may suitably be a petroleum fraction boiling in the kerosene, diesel, and gas-oil boiling range, and suitably may boil in the range from about 350 to about 850 F. Preferably, the gravity of the oil is in the range from about 42 to about '45 API. The water-soluble salt of lignin sulfonic acid suitably may be sodium, calcium, magnesium, or potassium salt, or mixing thereof. The salt functions as an emulsifying agent. In making the emulsion, either fresh or salt water may be used. It is preferable to use salt water, such as calcium chloride brine, calcium chloride and sodium chloride brine, and calcium chloride and calcium nitrate brines. Other brines, such as zinc chloride, sodium nitrate, Aand the like maybe employed. It is desirable to use brines or saltV solutions in the water phase in that the density of the' water emulsion may be controlled in the rangefrom about 8.5 to .about 14 pounds per gallon.

' With referenec nowto the drawing, in FIGS. 1, 2, and 3 there is shown a well installation comprising a casing 1 which is bonded to surrounding earth formations by a sheath 3. The casing is illustrated 'as havingV been perforated :at the level of a productive earth formation 11r to form' a plurality of perforations 19 and a plurality of perforations 21. It is desired to plug the perforations 19 and to thereafter produce the well through the perfomations 21. To this end a tubing string 7 is run into the Well having at its lower end slips 9 and an expandable packer 5. The packer seals the space between the lower `end of the tubing 7 and tlie Vcasing 1. The slurry described above containing the granulated sulfur particles ispumped down the tubing string 7 and sufficient hydraulic pressure is exerted to force the uid carrier and the granulated sulfur particles into the perforatiousV 19 and 21. Some of the iiuids 20 previously in the well bore will be forced out, leaving the level of the uids 20 at or below the lowermost of the perforations 19. The granulated sulfur will pack into all of the 'perforations 19 and 213as best illustrated in FIG. 1A, but after the nodules 15 have formed, there will be no tendency for a pack to form in the bore of the casing'l. The packer 5 may be deflated or decompressed to permit circulation of fluids up the annulus between the casing 1 and the tubing 7, Iand the slurry remaining in the bore of the casing 1 may be circulated to the earths surface and removed Yfrom the well.

Thereafter, a borehole heater 23 is lowered into the well adjacent the perforations '19 to be sealed.- Typically, the borehole heatermay be either electrically activatedor gas tired and may be of a num-ber of types well known to the art. The heater is activated to heat the sulfur particles in As is well known, sulfur does not have a sharp melting point, some of the particles melting before others of the particles. When the sulfur has been heated to melt a significant portion of the particles thereof, heating is discontinued. Inasmuch as many'of the sulfur particles have become` liqueiied, the particlesv will fuse together to form solid plugs in the .perforations 19, as best shown in FIG. 2A. Since the sulfur nodules in perforations 21 have not been particularly affected by the heater 23, the sulfur particles therein remain discrete. There,- after, as .illustrated in FIG. 3, the well is placed on production either by pumping or by naturally flowing the well so that the sulfur particles in .perforations Z1 are washed out of the .perforations into the well bore and removed from the well. `The fused plugs willtadhere to .the walls of the perforations in which they are formed, and so will remain in place therein as illustrated in FIG. 3;

,sulfur slurry remaining in the well bore.

An alternate method, desirable under some -circumstances, involves placement of the sulfur'slurry inthe perforations as follows:

(1) Run tubing string 7,without a packer 5, into the cased borehole until the lower end of :the tubing string is below the lowest perforation.

` (2) Circulate the vsulfur slurry down the tubing string t and back u'p the ltubing-casing annulus until the slurry con- -tacts and is opposite all perforations.

(3) Now, with sulfur slurry in contact with and op- .positeall perforations, stop yfluid vcirculation andincrease uid pressure in the borehole so as to cause filtration of the slurry into the perforations and build-up of the sulfur node 15.

(4) After sulfur nodes are formed, circulate out excess (5) Proceed, using the Wire line heater, to consolidate Ythe'sulfur selected .perforations as described above.

Still another method which may be Idesirable under cer- 'tain well conditions Vand which eliminates use of tubing .string 7, is to pump the sulfurslurry directly down the .casing'string, forcing well uids 20 ahead of the slurry and lback through perforations into 'the formation. ,sulfur slurryA reaches the perforation, the pumping pres- Vsure will increase as sulfur nodes form in the perforations, restricting uid flow.A This rincreased pressure is held a 'f xsuicient time to insure adequate node build-up, then `a When wire line heater runs to consolidate lselected perforations -as before;l Production of formation tiuids through per-y forations `21 removes excess slurry from the well bore.`

reliable. t

Having described the principle ofthe invention and the best modes in which we have contemplatedapplying that principle', We wish it to be understood that the apparatus described is illustrative only and that other means can beY :employed Withoutdeparting from the 'truescope of the invention.' t t t f What is claimed is:' v A 1. The method of plugging selected perforations in a cased and perforated well bore, comprising:

packing particulated sulfur into all of the perforations;Y heating the particulated sulfur in said selected perforations Yuntil the particulated sulfurV therein is fused 'together to form a plug that adheres to the walls of Vthe perfora-tions; and Y producing the well-.to remove 'theunfused sulfur partivcles from the perforations other than said selected yperforations.

cased and perforated well bore, comprising: t

n packing particulated sulfur into all of :the perforations;

activating a borehole heater adjacent said selected perforations to be plugged to heat the particulated sulfur therein until theV heated sulfur particles fuse together to form a plug that' adheres to the walls of the perforations; and f producing the well to remove the unfused sulfur particles from the perforations other than said Aselected perforations;r L f 3. Ihe method of plugging selected perforations inra'.

cased and perforated well bore, comprising:` Y n heating the particulated sulfurrin said selected perforations until the particulatedV sulfurV thereinl is fusedY together by lowering a borehole heater adjacent said selected perforations tor be plugged,and activating the borehole heater to heat the. particulated sulfur in perforations thereadjacent until the vheated lsulfur It is apparent from the above description of the above invention that many of the steps required according to .prior art'techniques for cementing and reperforating a well have'been eliminated. The number of wireline and pipe operations in the well have been reduced to a minimum. I lThe rinvention results in selective plugging of perforations in a well that willbeffound to'be Aextremely effectiveand Y 2. The method kofplugging selected .perforations in a particles are fused together to form a ,plugV thatadheres to the walls of ythe perforations; and

producing the well to remove the unfused sulfurfparticles from the perforations other than said iselected perforations. Y Y Y 4. The method of plugging selected .perforationsin a cased and perforated Well bore, comprising:

forming a suspension of particulated sulfur in a solidsfree oil-in-wateremulsionliquid vehicle;`

squeezing said liquid vehicle and particulated sulfurl suspension into all ofthe perforations until the perforations are packedwith lparticulated sulfur;

heatingthe particulated sulfur in said selected perforations until the particulated sulfur therein is fused `together to form a plug that adheres to the walls of the perforations; and

' producing the well to remove the unfused sulfurv-parti-` Y other than `said selected sulfur inthe perforations. thereadjacent until-the v heated sulfurparticles. are fused togetherto-jform plug 'thatadheres to the walls ofthe 'perforationsy` and producing-thegwell to remove the Yunfused sulfur particles from theperforations Aother than saidlselected perforations. Y Y f 6. The method of plugging selected cased and perforated well bore, comprising:

forming an emulsion comprising about 83%VY to aboutk 98% vby yolume of water, about l17.5 to about 10% sulfur per barrel -of Water and oil, said sulfur having 'particle sizes in theA range of from 4to 325 mesh, said Water-solublesalt of lignin sulfonic acid and oil being vpresent ina ratio of about 0.1to about 0.25 :1 vol- Y A.ume percent, said `emulsion having a density Within the range of from about 8.5 gallon; squeezingrsaid emulsion into all of said perforations untilgthe perforations are packed with Aparticulated sulfur; Y v Y t Y heating the .particulated sulfur Vin said selected perforations until the particulated sulfur thereinY is fused to-V v gether tol form a plu-g that adheres to the walls ofthe perforations; and I j producing the well to remove the unfused sulfur partip'erforationsv Y n v 7. The method of plugging selected perforations in a cased and perforated well bore, comprising:

forming an emulsionl comprising about 83%r to` about 98% by volume of Water, about 1.5 toabout 10% by volume of oil, a. VWater-soluble saltof lignin mesh, said water-soluble salt of ligningsulfonic acid and o'il being presentin a ratio of'about'0.1 'to about 0.25 :1 volume percent-said emulsion having-a density within the range of from-about 8.5 to about 14. pounds Y per gallon; Y

squeezing said emulsion" into vall of said perforations until the perforationsV are .packed with particulated Y Y sulfur; Y

activating the borehole heater to heat theV particulated .y v

perforations in fa by volume of oi-l, a water-soluble'saltfor lignin sul-` fonic acid, and from 1 to 100pounds of particulatedY Y to about Y14 pounds per cles from the perforationsother thank said selected.

sulfonic acid, andfrom l to'lOO pounds of particui lated sulfur'per barrelof Water and oil,rsaid sulfurk having` particle sizes `in the-range of from4gto 325 lowering a borehole heater adjacent said selected perforatons to be plugged; y

activating the borehole heater to heat the partioulated sulfur thereadjacent until the heated sulfur particles are fused together to form a plug that adheres to the Walls of the perforations; and

producing the well to remove the unfused sulfur particles from the perforations other than said selected perforations,

References Cited by the Examiner UNITED STATES PATENTS Cooper *166-25 Jackson et al 166-25 Reed 166-2'5 Schlumberger 166-25 CHARLES E. OCONNELL, Primary Examiner.

S. I. NOVOSAD, Assistant Examiner. 

1. THE METHOD OF PLUGGING SELECTED PERFORATIONS IN A CASED AND PERFORATED WELL BORE, COMPRISING: PACKING PARTICULATED SULFUR INTO ALL THE PERFORATIONS, HEATING THE PARTICULATED SULFUR IN SAID SELECTED PERFORATIONS UNTIL THE PARTICULATED SULFUR THERIN IS FUSED TOGETHER TO FORM A PLUG THAT ADHERES TO THE WALLS OF THER PERFORATIONS, AND PRODUCING THE WELL TO REMOVE THE UNFUSED SULFUR PARTICLES FROM THE PERFORATIONS OTHER THAN SAID SELECTED PERFORATIONS. 